Comments on: Loop Abstractions in D revisited

By: kl

kl — Wed, 16 Apr 2008 20:27:00 +0000

How about:
retry!(HTTPError,5)({code}); ?

maybe you could use mixin to create nicer syntax?

By: Javi

Javi — Sun, 03 Feb 2008 20:09:05 +0000

Ummm… it isn’t a bug, I wrote a function to call totry() N times. Rename retry() to CallNTimes() or something like that. ; )
My fault, I misunderstood the idea of the article.

Cheers!
Javi

By: Hans-Eric

Hans-Eric — Sun, 03 Feb 2008 19:26:48 +0000

Interesting approach. Using a delegate to control the flow opens some intriguing applications.
I think you introduced a small bug though: totry will always be invoked times time. Easily fixed. Just replace

totry();

with

totry(); return;

Cheers man!

By: Javi

Javi — Sat, 02 Feb 2008 15:22:05 +0000

I don't like templates... Why not something simple like this?:

void retry(uint times, void delegate() totry, void delegate(Exception) funcex=null) 
{ 
  for(uint i = 0; i < times; i++) 
  {
    try 
    {
      totry();
    } 
    catch(Exception ex) 
    { 
      if(funcex !is null) 
      { 
        funcex(ex); 

        // Or if you want to control the break the loop, 
        // define funcex as bool delegate(Exception) and: 
        // if(!funcex(ex)) 
        // { 
        //   break; 
        // }
      } 
    }
  } 
} 

// Some examples: 

// Executes MyFunc() 5 times catching all exceptions 
retry(5, &MyFunc); 

// Executes MyFunc() 5 times catching all exceptions 
// and pass them to HandleMyExceptions(Exception) 
retry(5, &MyFunc, &HandleMyExceptions); 

// More explicit examples: 
retry(5, { writefln("hola"); });  

retry(5, { writefln("hola"); throw(new Exception("error!")); }, delegate(Exception ex){ writefln(ex); });

Cheers, Javi